Integrative taxonomy supports one rather than several species of Palingenia in South-Eastern Europe (Insecta, Ephemeroptera, Palingeniidae)

Abstract Palingenia Burmeister, 1839, is a small but intensively debated genus of mayflies due to the controversial taxonomy of the species belonging to it. Once widespread throughout Europe, Palingenia longicauda (Olivier, 1791), an iconic species of large pristine rivers, has lost most of its original range, but conservation efforts are greatly hampered by its morphology, which is similar to the sympatric P. fuliginosa (Georgi, 1802) and the peripatric P. sublongicauda Tshernova, 1949. Based on the revision of Soldán’s original collection, supplemented with fresh material from southeastern Europe, we analyzed 213 adult male specimens from 15 different locations from the presently known distribution area of Palingenia in Europe. Principal Component Analysis (PCA) based on the morphometry results of penis morphology and eye distances showed no significant differences among the analyzed populations. Further, the mtCOI barcode sequence data of 73 individuals from the known range of Palingenia species in southeastern Europe represented highly similar populations genetically, with no differentiation. These results show the presence of only one species in southeastern Europe, P. longicauda, thus disproving the distribution of P. fuliginosa in this region. The taxonomic status of P. sublongicauda remains doubtful, as no type material or fresh material from the locus typicus of the species was available for this study. A comprehensive revision of Palingenia, including additional species from Asia and the Indomalayan regions, is highly recommended to reevaluate the species composition of Palingenia and detect the most closely related taxa of the single P. longicauda in Europe.